Congressional debate on President Barack Obama's request for authorisation to strike Syria intensified as Secretary of State John Kerry, Defence Secretary Chuck Hagel and General Martin Dempsey, Chairman of the Joint Chief of Staff, briefed the lawmakers on the Senate Foreign Relations Committee.
The actions of the Assad regime has threatened the US national security interest, they argued.
"In creating impunity, we will be creating opportunity - the opportunity for other dictators and terrorists to pursue their own weapons of mass destruction, including nuclear weapons," Kerry said.
"This is not the time for armchair isolationism. This is not the time to be spectators to a slaughter. Neither our country nor our conscience can afford the cost of silence," he said.
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Noting that the use of chemical weapons in Syria is not only an assault on humanity - it is a serious threat to America's national security interests and those of closest allies, Hagel said the Syrian regime's use of chemical weapons poses grave risks to US friends and partners along Syria's borders - including Israel, Jordan, Turkey, Lebanon and Iraq.
"Weakening this norm could embolden other regimes to acquire or use chemical weapons," Hagel said.
Opening up the Senate committee deliberations, Senate Foreign Relations Committee Chairman Robert Menendez said there are risks to action, but the consequences of inaction are greater and graver still: further humanitarian disaster in Syria; regional instability; the loss of American credibility around the world; an emboldened Iran and North Korea; and the disintegration of international law.
"The chemical weapons attack against innocent civilians in Syria is an indirect attack on America's security with broader implications for the region and the world.